Southern Thule

Geography & Climate

Southern Thule is located in United Kingdom, within the South Sandwich Volcanic Arc of the broader Antarctic-Scotia Volcanic Regions. Situated at 59.44° S, 27.23° W in the Southern Hemisphere, the volcano lies within a subarctic climate zone. With a summit elevation of 1,075 meters above sea level, Southern Thule is a moderately sized peak that remains accessible to hikers and researchers for much of the year. The volcanic landform is characterized as a composite, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Southern Thule sits in a subduction zone, where one tectonic plate dives beneath another, creating intense heat and pressure that generates magma. Subduction zones are responsible for many of the world's most explosive volcanoes and deadliest eruptions. For communities in United Kingdom near Southern Thule, this tectonic setting means the volcano is capable of producing powerful explosive eruptions, pyroclastic flows, and lahars that can threaten populated areas within tens of kilometers of the summit. The dominant rock type is andesite / basaltic andesite, a dark, fine-grained volcanic rock that forms from rapidly cooling, low-viscosity lava. Basaltic eruptions tend to be less explosive and produce fluid lava flows that can travel long distances. While less immediately dangerous than explosive eruptions, basaltic lava flows can destroy structures and infrastructure in their path, and volcanic gases released during these eruptions can affect air quality over a wide area.

Eruption History Summary

Southern Thule has 1 recorded eruption in the geological database, spanning from 1975 CE to 1975 CE. The most powerful recorded event was a gentle, effusive event in 1975 CE, reaching VEI 1 on the Volcanic Explosivity Index. The most recent eruption in 1975 CE places this volcano within the modern era of volcanological observation.

GVP Reference Summary

The Southern Thule island group, at the southern end of the South Sandwich island arc bordering the Scotia Sea, consist of three stratovolcanoes constructed along an E-W line. An ice-filled 1.5-2 km wide caldera truncates the summit of andesitic-dacitic Thule, the westernmost island, and a 4.3 x 4.8 km submarine caldera forms Douglas Strait between Thule and basaltic-to-dacitic Cook Island. Another possible submarine caldera lies east of Cook Island and south of basaltic andesite Bellingshausen, the easternmost island. The age of Cook Island is uncertain, but steam was observed at the summit crater of Thule Island in 1962, and ash was seen on the surface of the ice there and on Bellingshausen Island, indicating possible 20th-century eruptions (Baker, 1968). Bellingshausen has a youthful, relatively ice-free profile and an extensive well-preserved lava field on its S flank, where a small explosion crater formed sometime between 1964 and 1986.

— Smithsonian Institution, Global Volcanism Program